SAML2 Authentication on Sentry with Keycloak

I have installed Sentry on-promice 20.9.0 and I try to integration of the sentry with the keycloak via SAML2 authentification.
I configured my Sentry according to: Custom SAML Provider | Sentry Documentation
Map identity:

And authentification is works well.
When existing user try to login via SAML2, he receives this notification:

and pressed “Continue”.
But, Sentry creates a new account with a strange Username and an existing email:

I need to link to existing account.
Any help would be helpful.

This sounds similar to SAML2: Sometimes users account is duplicated. · Issue #25345 · getsentry/sentry · GitHub

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